Automatic progressive hem forming mechanism

ABSTRACT

Novel pneumatic means is employed for marginally forming flexible sheet material as in over or under-edging fabric being fed into a sewing machine for hemming. One or more roll-shaped preformers are each provided with an air jet channel extending normal to the direction of work feeding as determined by perforated inner, aligned edge gage portions of the formers. The latter are preferably laterally movable to urge the semi-formed margin progressively through a final, stationary, open-ended former which is tapered in the direction of feeding to a relatively flat section arranged to project the fully formed hem into the stitching zone. Accuracy in &#39;&#39;&#39;&#39;square&#39;&#39;&#39;&#39; folding the leading edge is attained, and a large range of work varying from very flimsy to relatively stiff can be handled in automatic manner. An optional vibrator facilitates forming the stiffer material but, with the same air flows does not increase the tendency of limp material to collapse and clog.

Morgan [111 3,776,156 51 Dec. 4, 1973 AUTOMATIC PROGRESSIVE I-IEM FORMING MECHANISM [75] Inventor: Paul E. Morgan, Melrose, Mass.

[73] Assignee: USM Corporation, Flemington, NJ.

[22] Filed: Mar. 14, 1972 [21] Appl. No.: 234,577

[52] US. Cl 112/141, 270/69, 270/93 [51] Int. Cl D05b 35/02 [58] Field of Search ..112/141-143, 147,152,153, 63,10,121.l1,

121.12, 121.15, 121.29, 203, D1G.1, DIG. 2, DIG. 3, 102-103, 118, 86; 270/61 R, 69, 93; 271/59, 74

[5 6] References Cited UNITED STATES PATENTS 3,595,187 7/1971 Gray 112/141 3,550,964 12/ 1970 Spyropoulos 271 /74 X 3,204,591 9/1965 Pickett 112/D1G. 2 3,192,885 7/1965 Timm.... 112/140 3,252,437 5/1966 Pickett 112/DIG. 2

3,401,655 9/1968 Johnson et a1 112/147 X 3,537,704 11/1970 Bond 271/74 Ogbum 1 12 141 Primary Examiner-James R. Boler Assistant Examiner--Peter Nerbun AttorneyRichard B. Megley et al.

[5 7 ABSTRACT.

stitching zone. Accuracy in square folding thev leading edge is attained, and a large range of work varying from very flimsy to relatively stiff can handled in automatic manner.

An optional vibrator facilitates forming the stiffer material but, with the same air flows does not increase the tendency of limp material to collapse and clog.

20 Claims, 18 Drawing Figures PATENTED v4 I975 SHEET 1 [IF 7 PAIENTEDHEB 41975 sum 30? 7 \NWD, E /cww\ v QQ Q Q QQ E E SHEET 8n;

afnalss, 7

PATENTEU DEC 41915 ammo/P 70 AUTOMATIC PROGRESSIVE I-IEM FORMING MECHANISM CROSS REFERENCE TO RELATED APPLICATIONS An allowed U. S. Pat. application Ser. No. 9,185 filed Feb. 6, 1970 in my name, now US. Pat. 3,631,826 relates to an air flow device for orienting sheet material relative to an operating instrumentality.

Another U. S. application, Ser. No. 167,690 filed July 30, 1971 in the name of Richard W. Gray pertains to a hemming machine employing air flow.

Additionally, a hemming accessory employing air flow is disclosed in an allowed application Ser. No. 6,510 filed Jan. 28, 1970 in the name of Richard W. Gray, now issued as US. Pat. No. 3,595,187.

BACKGROUND OF THE INVENTION The present invention pertains to positioning and forming of flexible sheet material, and more especially to improved hem forming and edge guidance mechanism as combined and adapted for use with sewing or other margin securing machines incorporating linear work feeding mechanism.

In addition to the approaches disclosed in the above cited applications, various other guidance and hemming devices have been provided which employ air flow to facilitate movement and positioning of :1V sheet material being processed. For instance the prior art includes U. S. Letters Pat. Nos. 3,018,746 Winberg; 3,204,590 Rockerath et al.; 3,192,885 Timm; 3,204,591 Pickett; and 3,252,437 Pickett. While the known devices are in many cases helpful to-a ma chine operator in manipulating one type of flabby work piece, it is generally found that, especially in apparel making and other industries becoming more automated.

and involving large volume production, greater versatility in rapidly and efficiently dealing with many. different types of flexible sheet material is becoming very important. In general the known hemming devices, if they can form and guide one type of fabric or the like, will jam upon receiving other sheet material of different physical characteristics, the degree of material stiffness often proving critical.

SUMMARY OF THE INVENTION It accordingly is a principle object of thisinvention to provide, for use with a sewing machine or other margin securing means, a hemming and guidance mechanism capable of precisely forming the margins-of'flexible work pieces having a wide range of physical characteristics and then progressively presenting the formed.

margin properly to the securing means.

A further and more specific object of this invention having an edge gage portion and a roll surface prefera-. bly including an internal channel extending to this edge gage portion for directing an air jet or stream to augment by Bernouilli principle the frictional relation of a work piece being urged around the roll surface and into alignment with the gage position. The arrangement desirable is such that when the flexible sheet material, a fabric for instance, has been introduced edgewise to the plurality of formers (as by an automatic feeder of the type disclosed in US. Letters Pat. No. 3,531,103 issued Sept. 29, 1970 in the name of R. R. Walton, for example), the edge of the fabric will first be urged circumferentially about the formers, including the mouth end of the final former, and into abutment with the edge gage portion. This edge contact is maintained, for instance held square with a leading side edge, as the movable preformer(s) now jointly urge the work laterally toward the sewing machine, the leading-portion of the preformed margin being progressively advanced through the stationary former. A flatter end of this fixed former, which has smaller radii of curvature nearer the needle and .would therefor offer greater resistance to folding movement of the work, thus is enabled progressively to project flattened leading marginal portions of the work into the operating zone of the sewing needle and its cooperative feed-dog and presser foot. In this manner the usual approach involv ing a pushing of the flexible work piece, which customarily produces buckling and jamming of the work piece in the'hemmer, is avoided.

Though usually preferable to move the preformers laterally to advance the work progressively through the final former, an alternative arrangement (not specifically illustrated) of the invention contemplates holding the formers stationary, with their inner edge gages aligned and maintaining the margin forming peripheries of the differently shaped cross sections of substantially equal length, and relying upon other mechanism for feeding the work toward the margin securing instru mentalities to'be progressively formed, flattened and hemmed while the work margin is in contact with the gages. The importance of the feature of equal peripheral length in the formers, whether they be relatively movable or not, lies in the fact that the cloth can be progressively flattened at its folded margin and presented squarely to the margin securing means.

Additionalnovel features and niceties which may be noted, though not restricted to those mentioned'by way of example, pertain to the provision of lower air flow, hence improved efficiency, as permitted by turbulenceavoiding air dump holes in the edge gage portions of the preformers which increase insensitivity to the degree of stiffness in the work pieces; provision of sharper by means of the shape of the formers and their jet air channels; provision of wider range of material handling capability by means of a fabric vibrator; and provision of a valve automatically responsive to the presence of .the work edge at the edge gage for signalling for lateral ceive the next work piece.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other features of the invention together with various novel details in construction will now be more particularly described in connection with an illustrative embodiment, and with reference to the accompanying drawings thereof, in which:

FIG. 1 is a plan view of an edge guide and hemming mechanism as adapted for down-turn hemming in a sewing machine, parts of the mechanism being shown with its formers in position for accepting work from an input feeding means (not shown);

FIG. 2 is a view similar to FIG. 1 but showing the margin preformers when shifted laterally to transfer the work toward the stitcher and through a final former;

FIG. 3 is a perspective view of the mechanism shown in FIG. 1;

FIG. 4 is a'view similar to FIG. 3 but showing the work laterally fed and with its formed hem being stitched;

FIG. 5 is a detailed perspective view of one of the preformers and a sensing means by which stitcher starting, preformer translation, and air jet pressure are automatically controlled;

7 FIG. 6 is a view in front elevation, partly in section, showing the mechanism in its initial work receiving position as indicated in FIG. 1;

FIG. 7 is a view in front elevation similar to FIG. 6 but showing the parts as thereafter shifted toward the stitcher as indicated in FIG. 2;

FIG. 8 is a vertical section taken looking away from the stitcher and showing the mounting of the'sensor and preformer of FIG. 5 and associated vibrator mechanism;

FIG. 9 is a vertical section corresponding to that of FIG. 8 but looking toward the stitcher;

FIG. 10 is an end view of the final former looking into its exit end from the stitcher needle;

FIG. 11 is a section of the final former taken on the line XI-XI of FIG. 1;

FIG. 12 is a section of the final former taken on the line XIIXII of FIG. 6;

FIG. 13 is an end view of a longer preformer as seen looking in the direction of the arrows XIIIXIII of FIG. 1;

FIG. 14 is a section, on a larger scale, of a shorter.

preformer taken on the line XIV-XIV of FIG. 1;

FIG. 15 is a transverse section of a preformer indicating how a portion of a fabric work piece is bowed;

FIG. 16 is a timing chart for one cycle of the machine and showing operation on one type of fabric;

FIG. 17 is a view corresponding to a portion of FIG. 4 and showing an optional modification for providing additional work support; and

FIG. 18 is a largely diagrammatic view of optional control means for providing a variable and proper degree of infeed air flow as determined by the work itself.

DESCRIPTION OF THE PREFERRED EMBODIMENT Application of the invention will be described, by way of illustration though not limited thereto, as provided for use with a sewing machine not fully shown tal bed including a throat plate 12, and adapted for down-turn hemming of a workpiece W as shown in FIG. 4. Also, it is contemplated that the illustrated machine will be automatically fed by a cyclical fabric destacking machine, for example one of the type disclosed in U. S. Letters Pat. No. 3,531,103 issued Sept. 29, 1970 in the name of R. R. Walton, but may of course be manually or otherwise fed when and if desired.

Secured to an edge of a tabel 14 (FIGS. 1, 2, 8 and 9), the top 16 of which is substantially parallel to and 1 may be an extension of the sewing machine'bed, is a pair of brackets l8, 18 (FIGS. 1, 2, 8 and 9). The latter support a fixed angle iron 20 carrying mechanism for moving a work support plate 22 and spaced work supporting extensions 23 thereof laterally in reciprocal translation as will next be described and parallel to the seam to be stitched by the needle 10. For this purpose a stationary air-pressurized cylinder 24 (FIGS. 1, 2, 6 and'7) having a return spring (not shown) and secured at one end to an underside of the angle iron 20 is provided with a piston rod 26 connected by a clevis 28 and a bracket 30 to a plate 32. The latter is connected to one end of a horizontal slide rod 34 guided in bearing blocks 36, 38. These blocks are secured to the angle iron 20. The work support means 22, 23 is secured on the plate 32 as shown in FIGS. 8 and 9, and guide rollers 40 rotatably carried by the plate 32 are retained in angular guide ways 42 secured to the angle iron 20.

Hem preforming means next to be described is con-. nected for joint lateral movement with the slide plate 32 by an angle iron 44 (FIGS. 8 and 9) and an upright support 46 secured thereto. A plurality of preformer units generally designated 48 and a wider preformer 49 are aligned and respectively spaced apart by the work support extensions 23, the number being dictated largely by the length of the margin to be hemmed. Each unit 48 or 49 as shown in FIGS. 3 and 4 includes an inclined deflector portion 50 extending over the work support plate 22, a horizontal portion 52 which merges into a cylindrical roll portion 54, and an internal end stop or gage portion 56 which, for a reason later noted, is formed with air dump holes 58. The several end gage portions 56 and their holes 58 are aligned and disposed parallel to the hem stitching to be performed. Importantly, eachof the preformers 48 and 49 initially are to bend a-portion of the work W into some part of a circular roll, and to this end are preferably formed internally and normal to the edge gage 56 with a high speed air groove 60 that communicates with a nozzle 62 in the portion 52 that is preferably rather close to the roll portion 54. The grooves 60 advantageously direct and maintain higher air path velocity and extend the Bernouilli effect farther into the preformers than is possible without them thereby tending less to collapse the fabric.

Accordingly, the work is presented by the infeed mechanism on the support 22 to the formers 48, 49 just beyond the nozzles 62, and the laterally leading edge of the work W is presented into a transistion portion 63 and partly into an adjacent end portion of a stationary final hem former 64. It is to be observed that the jet air flows between the work fabric and the inside surface of the hem formers, the velocity of the air causing a localized pressure drop (Bemouilli efiect) whereby atmospheric pressure tends to hold the fabric against the inside surface of the preformers. The function of the translation portion 63 is to prevent buckling during preforming and during translation.

In order to, in effect, temporarily stiffen portions of flimsier fabrics to be hemmed and thereby guard against their collapse and hence blockage of their formers, each unit 48 may be arched slightly in a transverse direction or, preferably and as shown in FIG. 15, lateral edges 66, 66 may simply be intumed parallel to the air path groove 60 to serve as spacers for locally bowing the cloth. The Bernouilli effect induced by the high speed air feed causes the fabric adjacent to the groove 60 to tend to conform or stickclosely to the former inside surface, and the transverse curvature enables even the flimsier work W to be advanced fully into the preformers for abutment with the edge gages 56. The air dump holes 58 require a lower volume of air flow to be supplied in view of turbulence elimination and therefore act to increase the stiffness insensitivity range of the work.

A vibrator 68 (FIGS. 8 and 9) may optionally be secured to the angle iron 44 to facilitate margin forming of stiffer materials W without increasing the collapsing tendency of limp materials, and for the same air flow.

When the hem forming mechanism being described is cylically fed by an automatic feeder as contemplated and indicated in the timing chart of FIG. 16, the infeed stroke terminates and the single work piece W is released on the plate 22 to the further infeeding influence of the air jets 62. FIG. 16 also indicates the sequence as the infeeder retracts, high pressure air to the grooves 60 and other air forming nozzles being called for at the time of work release so as to curl the entire margincircularly within the preformers 48 and 49 and the former 64. As shown in FIGS. 6-9, there is mounted between a pair of preformers units 48 a sensing means in the form of a whisker valve 70 bracketed on the angle iron 44 for signalling when the rolled margin has been initially fully formed to the required degree. To this end the valve 70 is connected by a deflectable slender wire form 72, an internal end 74 of which is displaceable by the work margin reaching the adjacent end gage 56 and thereby producing three results:

I. The cylinder 24 is pressurized laterally to shift the preformers 48 and work supports 22, 23 together with the preformed work W leftward from the position shown in FIG. 3 to that shown in FIG. 4;

FIG. 2. Operation of the sewing machine is initiated automatically, and

3. The air pressure in nozzles 62', etc., is reduced.

The transition portion 63 of the final hem former 64, which is secured by brackets 76 to the angle iron 20, is formed with substantially uniform inside diameter and disposed to receive in substantially endwise telescoping relation the preformers 49 and the partially preformed hem which is thereafter to be progressively tapered and flattened as it is further advanced to and through the operation path of the needle 10 and its associated presser foot and feed dog mechanism (not shown). Aiding in the lateral advancing of the work'W, in addition to friction between the carrying work support portions 22, 23 and the work, is the influence of the Bernouilli effect at each of the high speed air jet the vicinity of a tapering portion 82 of the final former 64 and along the work supporting surface of a bracket 83 affixed to the angle iron 20. The contour of the tapering portion 82, considered in the direction of work advance, gradually changes from a shape substantially that of the preformer and having relatively large radii of curvature to an exit end which is quite flat and includes relatively small radii of curvature and an internal lip 84. For aiding in the final hem forming a pair of air nozzles 80, 81 coupled to a common source of air pressure with the nozzles 62 extend to emit flow tangentially downward within the portion 82 and with different angles each having a component in the direction of feed. Accordingly when the needle 10 operates upon the emerging, progressively flattened hem, the seam passes through three plies, the last one having been in turned by the former portion adjacent to the lip 84 to hide a raw edge of the work, as shown in FIG. 4.

It may be noted that no air dumping holes are provided in the final former 64 since they would interfere with the lateral feeding of the work therein. In order to maintain straight line feeding the different work engaging transverse sections of the preformers and final former are of equal peripheral length.

The: wider preformer 49 preferably has infeed air flow provided in one groove 60 from a nozzle 62 and also from a second nozzle 85 (FIGS. 3 and 4) which emits its stream normal to the end gage portion and along a non-grooved internal surface. In like manner an intermediate upper portion of the final former 64 is non-grooved and receives air flow for aiding in urging the work margin to be fully conformed to the smaller radii of internal curvature. As shown in FIGS. 10 and 12 an air jet inlet 88 is provided in the lower portion of the final former 64 adjacent to its exit end to insure that the work W'is maintained in edge contact with the lip 84 despite sharper curvature being negotiated there.

Inlet air streams are directed tangentially of internal work guidance surfaces rather than at an angle thereto with the preformers 48, 49 laterally retract, i.e., to the right in FIGS. l4, to their starting positions without disturbing hem formation of that final portion of the margin about to be laterally drawn to the left through the final former 64. Infeeding of a new work piece to be hemmed may commence as soon as the supports 22, 23 have returned to receive it, whereupon the cycle is repeated.

It should be noted that the air path grooves 60 require only low volume air flow, and this is so for the grooves 60'even when the high pressure is on since the jet is then one of high speed but needs only be of small (about 0.025 X 0.040 inches) in cross section.

As indicated in FIG. 17, it may be desirable for handling the more limp types-of work pieces to provide air work guides 90. These are secured to the extensions 23 and have curled under end portions 92 formed with somewhat smaller diameter and aligned with the preformer portions 54.

An optional feature generally found to be very desirable from the standpoint of broadening capability of the machine in properly handling different sheet materials will now be explained with particular reference to FIG. 18. It pertains to control means, shown largely diagrammatically in FIG. 18, whereby the infeed air pressure to a manifold (not shown) interconnecting all the former nozzles 62 and others is intensified automatically over an air draw in interval to the degree required (see FIG. 16) by any particular workpiece, but no more than necessary, to cause it to move edgewise fully into actuating engagement with the whisker valve 70, whereupon a reduced air pressure is provided. This control includes a fluid pressure circuit which, if associated with an automatic fabric feeder of the sort previously alluded to may be operated from a fluid logic system, but which may in fact also be associated with a manual, i.e., treadle controlled feed mechanism or other infeed mechanism.

When air pressure at the start of operations is turned on, air flows through pressure regulator valve 100 (FIG. 18), through two-way valve 102, is stopped by a check valve 104 and three-way valve 106, and therefor flows into the pilot control of a pressure regulator valve 108. This permits the valve 108 to be ready to deliver air to the nozzles 62 and the others at a preselected minimum air pressure and flow level whenever a main valve 110 is opened, with no delay in coming to that level. The minimum level is initially adjusted suitably at regulator valve 100. An operator, or the automatic feeder, now places the work piece W to be hemmed in front of the hem formers 48, 49 and 64 and on the order of about within one-fourth inch in any direction from an optimum position. By treadle pilot valve if feeding is manual, or by pilot valve at the end of an automatic fabric feeding in-stroke, a start signal is given to a draw-in valve 114 (FIG. 18) which is shifted to supply air to a line 116 switching a shuttle valve and thus immediately pressurizes a line 112 which opens the main valve 110. This at once sends pressurized air to the hemmer nozzles 62 etc. at the preset level referred to above. It may be noted that other circuitry holds the valve 114 shifted until a later actuation of a hold-in" pilot valve 120. The air draw-in actuation of the valve 114 also immediately closes the two-way valve 102.

Pressurized air also passes through flow-control regulator 122 and the check valve 104 to the pilot or control side of the regulator 108. This causes it to build up air pressure and air flow to the nozzles 62, etc., via an outlet 124 (FIG. 18), the rate of increase being determined by the presetting of the flow control regulator 122. The leading or inner edge of the fabric being presented is drawn by the air jets in the hem formers at a rate self-determined by its particular weight and stiffness, flimsy cloth filling the hemmers very quickly, and heavy, stiffer work pieces entering and being conformed in the hemmers more slowly. During this action the air pressure at the nozzles 62 etc. is rising as explained until the fabric is fully seated in the hem formers and has actuated the sensor 70. The relatively heavier and/or stifler cloth requiring more jet air flow automatically acquires it because its slower entry into the formers produces higher nozzle iar pressure. In contrast thereto, flimsier fabric, which probably would crumple and jam up under a high air flow, moves into the formers so fast that nozzle pressure (and flow) hastends to buckle flimsy material therein, and a flow adequate to hold the flimsy material conformed would not suffice to maintain stiffer material fully conformed. By means of the whisker sensor being operated by the fully positioned and formed fabric margin, a signal actuates the hold pilotvalve 120 to pressurize a line 126 (FIG. 18) and repositions the draw-valve 114 to its normally closed position. The main valve remains open and actuated because air now passing through the hold pilot valve shifts the ball of the shuttle valve 118 maintaining main valve 1l0s pilot pressure. The valve 102 remains actuated and the check valve 104 prevents flow-back to exhaust. The three-way valve 106 is also actuated. The valve 102 will not permit air passage in either direction, while the valve 106 now allows air to pass through to an adjustable (preset) volume chamber 128 (FIG. 18). The valve 102 being closed, no air is being added, and the air trapped at the achieved pressure in the control chamber of the regulator 108 and its supply lines can now flow toward the chamber 128 until uniform pressure is, almost at once, attained in the regulator 108 and the chamber 128. since the latter had been at atmospheric pressure, the new pressure in the control chamber of the regulator 108 has now dropped to a portion of the level it had reached earlier in the cycle. The proportional pressure reached is adjustable during setting up of the machine by suitably changing the volume of the chamber 128. consequently, the pressure drop in the control chamber of the regulator 108 produces a regulated and reduced air pressure (and flow) via the outlet 124 to the hem mers which is proportional to the pressurebuild up and air flow required during the prior air draw-in." This means that the reduced air holding pressure is now appropriately proportional also to the stifi'ness and weight of the particular fabric about to be hemmed.

As previously explained, the actuating sensor 70 also signals the sewing machine to start, and the loaded preformers 48, 49 to move laterally toward the stitcher while advancing the fabric margin progressively through the final former 64. The shaped hem emerges from the final former toward the feed action of the feed dogs which then operate to effect progressive forming and stitching of the entire hem length. Deactuation of the sensor 70 by passage of the margin therefrom reverses the air cylinder 54 to return the preformers 48, 49 as above explained. Time delay circuitry not shown enables the trailing edge of the hem to pass through the stitcher before the stitcher stops and the hold signal on the valve 120 is removed.

The invention and its embodiment described herein assure versatility in dealing with flexible material having a range of stiffness and surface characteristics whereby continued accurate hemming operations, whether of down-tum or up-tum types, may be automatically and reliably provided.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the US.

l. A hemming and guidance mechanism for use with a machine having a work feeding mechanism and a margin securing means, said mechanism comprising a translatable work support, at least one margin preformer mounted on the support, mechanism for moving the work support and preformer toward and from the margin securing means, and a final stationary margin former at least in part laterally tapered and having its exit end disposed adjacent to said means and a work receiving end substantially in telescoping relation to the preformer.

2. A hemming and guidance mechanism as set forth in claim 1 wherein the preformer includes a roll portion and the final former is tapered from a diameter corresponding to that of the roll portion and at said-exit end shaped with smaller radii of curvature thanthe roll portion to progressively flatten the work margin as it is laterally fed to the securing means.

3. A mechanism as set forth in claim 1 wherein the preformer is provided with nozzle means for flowingair between the work and the preformer, and an air stream groove to enable a portion of the work piece to tendto cling and conform to the former by Bernouilli effect.

4. A mechanism as set forth in claim lwherein a plurality of preformers and the final former are respectively provided with at least partly circumferential hem forming roll portions terminating in aligned edge gages parallel to the margin to be formed, and air nozzles for urging work margin portions to abut the end gages.

5. A mechanism as set forth in claim 4wherein said gages in the preformers are formed with air dump holes to avoid turbulence therein.

6. A hemming and guidance mechanism for use with a sewing machine having a reciprocable meedle and means for feeding a work piece to and through the operating zone of the needle, said mechanism comprising a stationary final hem former having progressively decreasing radii of internal curvature and increasing width toward its exit end adjacent to the needle, and laterally movable work supporting means including hem preformers respectively provided with roll portions of internal radii of curvature substantially as large as that of the entrance end of the final former, the preformers having aligned edge gages, means for inducing a Bernouilli effect between a flexible work piece to be hemmed and the preformers, and fluid pressure means .for causing the preformers to carry the work piece laterally with its partially formed margin to urge the latter through the final former and then into operative relation with the sewing machine feeding means.

7. A hemming mechanism as set forth in claim 6 wherein each preformer has an air path groove for directing an air stream toward its end gage portion, and the latter is perforated.

8. A hemming machine as in claim 6 wherein the final former has a work receiving end arranged to telescope with a portion of a preformer and progressively receive the partially formed margin therein, and a nozzle is disposed to direct air flow tangential with an internal surface of the final former to urge the work as it approaches the exit end to conform with said decreasing radii of curvature.

9. A machine as set forth in claim 6 wherein pneumatic mechanism is provided for reciprocably operating said work supportingmeans relative to the final former, and sensing meansresponsive to relative movement of approach of the work margin and one of said gages is effective to energize said pneumatic mechanism to shift the work supporting means,

10. A machine as set, forth in claim 9 wherein said sensing means is further effective to control operation of the sewing machine. 7

ll. Hemming apparatus comprising a I sewing machine having stitch forming instrumentalities and work feeding mechanism for advancing a work piece thereto over a bed, hemming means including, in alignment, a final former and a plurality of preformers movable laterally and arranged for operation in the general plane of said bed, the final former having an exit end adjacent to said feeding mechanism and an entrance end remote therefrom and shaped with larger radii of internal curvature, each of said preformers having a circular portion for initially partly forming a margin of the work and-further including agrooved work supporting infeed surface, mechanism for cyclically moving the preformers laterally relative to the stitching instrumentalities to carry a portion of the preformed work margin through the'final former and then retract therefrom, cyclical infeed mechanism for automatically presenting successive work pieces into the preformers when they are retracted, and means for directing an air stream into the respective grooves of said work support infeed surfaces to urge the work into said circular portions and increase the tendency of portions of the work to stick to said surfaces.

12. Apparatus as set forth in claim 1 1 wherein at least one of the preformers has its grooved infeed surface I provided with opposedportions extending parallel to brator is associated with the preformers. i

15. For use with a machine having margin securing means, a hem forming mechanism comprising at least one work support for slidably receiving the flexible, perforate work to be hemmed, at least one roll-type former mounted on the work support and terminating in an inner end gage portion, said former having an air stream groove for causing an air jet therein to conform a margin of the work and direct it edgewise against said gage portion, means forsupplying air under pressure via a nozzle to the air stream groove, and control means for automatically regulating the pressure and flow of the air supplied to the nozzle according to the relative weight and stifiness of the work piece to be hemmed whereby it is advanced toward the gage portion and conformed to the former without being jammed or crumpled.

16. Hem forming mechanism as set forth in claim 15 wherein the control means further includes mechanism automatically operative, when a leading edge of the work margin contacts said gage portion, to decrease at the nozzle the air pressure, which had been required to effect the initial rapid contact of the margin with the gage portion, to a work holding level, the decrease in air pressure effected being automatically proportionate to the weight and stiffness of the work piece.

17. A machine having a margin securing means as set forth in claim 15, and further characterized in that the hem forming mechanism includes a final hem former, and means responsive to operation of said control means for laterally moving the preformer to advance the preformed margin into the final former and toward the operating zone of said meachine.

18. A machine as set forth in claim 15 wherein the machine has a work feeding mechanism, and the inner end gage portion of the preformer is aligned with the path of feed effected by the work feeding mechanism, and the end gage is perforated to dump air delivered from said air stream groove.

19. Mechanism for forming the margin of flexible sheet material to be hemmed, which material may range in different work pieces, respectively, in weight and/or stiffness, the mechanism comprising a hem securing tool, a work support movable toward and from the tool, at least a pair of margin formers mounted on the work support and having roll surfaces terminating in aligned end gages, an air stream groove extending in the respective roll surfaces substantially normal to the end gages, and control means including a nozzle for directing air flow with different velocities in the air stream grooves toward the end gages, said control means including a regulator means responsive to the degree of weight and/or stiffness of the sheet material for providing adequate air flow to effect engagement of the sheet material edgewise with the gages without incurring buckling of the material along the roll surfaces.

20. A hemming machine comprising stitch forming instrumentalities, a work supporting means adjacent thereto, at least one margin preformer disposed for receiving work on said means and spaced from the instrumentalities and having a roll portion terminating in an inner edge gage, a final margin former intermediate the preformer and saidinstrumentalities, the final former having an edge gage aligned with that of the preformer and a portion shaped with a cross section tapering to a flattened exit end, the work engaging surface of the preformer being formed with an air stream groove extending toward the roll portion to extend the Bernouilli effect when air flow is directed between said surface and the work and toward the inner edge gage, the margin forming peripheries of the cross sections of the preformer and final former being substantially equal in length, and mechanism for advancing the work over the work supporting means andtowards the instrumentalities to be progressively formed and hemmed when its margin is in contact with the aligned edge gages.

@2 3 UNITED .:'STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,776,156 Dated December 4, 1973 I -Inventor(s) Paul E. Morgan It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the claims:

Column 9, line 6, after said and before Claim 1, mechanism, insert ---hemming and guidance-- Column 11, line 10, change meachine to Claim 17,

---machine--- (SEAL) UActest:

EDWARD PLFLETCIERJR, 1 v C MARSHALL DANN Attesting Officer 1 Commissioner of Patent 

1. A hemming and guidance mechanism for use with a machine having a work feeding mechanism and a margin securing means, said mechanism comprising a translatable work support, at least one margin preformer mounted on the support, mechanism for moving the work support and preformer toward and from the margin securing means, and a final stationary margin former at least in part laterally tapered and having its exit end disposed adjacent to said means and a work receiving end substantially in telescoping relation to the preformer.
 2. A hemming and guidance mechanism as set forth in claim 1 wherein the preformer includes a roll portion and the final former is tapered from a diameter corresponding to that of the roll portion and at said exit end shaped with smaller radii of curvature than the roll portion to progressively flatten the work margin as it is laterally fed to the securing means.
 3. A mechanism as set forth in claim 1 wherein the preformer is provided with nozzle means for flowing air between the work and the preformer, and an air stream groove to enable a portion of the work piece to tend to cling and conform to the former by Bernouilli effect.
 4. A mechanism as set forth in claim 1 wherein a plurality of preformers and the final former are respectively provided with at least partly circumferential hem forming roll portions terminating in aligned edge gages parallel to the margin to be formed, and air nozzles for urging work margin portions to abut the end gages.
 5. A mechanism as set forth in claim 4 wherein said gages in the preformers are formed with air dump holes to avoid turbulence therein.
 6. A hemming and guidance mechanism for use with a sewing machine having a reciprocable meedle and means for feeding a work piece to and through the operating zone of the needle, said mechanism comprising a stationary final hem former having progressively decreasing radii of internal curvature and increasing width toward its exit end adjacent to the needle, and laterally movable work supporting means including hem preformers respectively provided with roll portions of internal radii of curvature substantially as large as that of the entrance end of the final former, the preformers having aligned edge gages, means for inducing a Bernouilli effect between a flexible work piece to be hemmed and the preformers, and fluid pressure means for causing the preformers to carry the work piece laterally with its partially formed margin to urge the latter through the final former and then into operative relation with the sewing machine feeding means.
 7. A hemming mechanism as set forth in claim 6 wherein each preformer has an air path groove for directing an air stream toward its end gage portion, and the latter is perforated.
 8. A hemming machine as in claim 6 wherein the final former has a work receiving end arranged to telescope with a portion of a preformer and progressively receive the partially formed margin therein, and a nozzle is disposed to direct air flow tangential with an internal surface of the final former to urge the work as it approaches the exit end to conform with said decreasing radii of curvature.
 9. A machine as set forth in claim 6 wherein pneumatic mechanism is provided for reciprocably operating said work supporting means relative to the final former, and sensing means responsive to relative movement of approach of the work margin and one of said gages is effective to energize said pneumatic mechanism to shift the work supporting means.
 10. A machine as set forth in claim 9 wherein said sensing means is further effective to control operation of the sewing machine.
 11. Hemming apparatus comprising a sewing machine having stitch forming instrumentalities and work feeding mechanism for advancing a work piece thereto over a bed, hemming means including, in alignment, a final former and a plurality of preformers movable laterally and arranged for operation in the general plane of said bed, the final former having an exit end adjacent to said feeding mechanism and an entrance end remote therefrom and shaped with larger radii of internal curvature, each of said preformers having a circular portion for initially partly forming a margin of the work and further including a grooved work supporting infeed surface, mechanism for cyclically moving the preformers laterally relative to the stitching instrumentalities to carry a portion of the preformed work margin through the final former and then retract therefrom, cyclical infeed mechanism for automatically presenting successive work pieces into the preformers when they are retracted, and means for directing an air stream into the respective grooves of said work support infeed surfaces to urge the work into said circular portions and increase the tendency of portions of the work to stick to said surfaces.
 12. Apparatus as set forth in claim 11 wherein at least one of the preformers has its grooved infeed surface provided with opposed portions extending parallel to the direction of infeed and adapted transversely to bow a portion of the work piece for stiffening it.
 13. Apparatus as set forth in claim 11 wherein a sensor is disposed adjacent to the circular portion of one of said preformers for reacting to advancement therein of the work margin to a predetermined point, said sensor being effective to control the lateral shifting of the preformers in time relation to operation of the sewing machine and of the infeed mechanism.
 14. Apparatus as set forth in claim 11 wherein a vibrator is associated with the preformers.
 15. For use with a machine having margin securing means, a hem forming mechanism comprising at least one work support for slidably receiving the flexible, perforate work to be hemmed, at least one roll-type former mounted on the work support and terminating in an inner end gage portion, said former having an air stream groove for causing an air jet therein to conform a margin of the work and direct it edgewise against said gage portion, means for supplying air under pressure via a nozzle to the air stream groove, and control means for automatically regulating the pressure and flow of the air supplied to the nozzle according to the relative weight and stiffness of the work piece to be hemmed whereby it is advanced toward the gage portion and conformed to the former without being jammed or crumpled.
 16. Hem forming mechanism as set forth in claim 15 wherein the control means further includes mechanism automatically operative, when a leading edge of the work margin contacts said gage Portion, to decrease at the nozzle the air pressure, which had been required to effect the initial rapid contact of the margin with the gage portion, to a work holding level, the decrease in air pressure effected being automatically proportionate to the weight and stiffness of the work piece.
 17. A machine having a margin securing means as set forth in claim 15, and further characterized in that the hem forming mechanism includes a final hem former, and means responsive to operation of said control means for laterally moving the preformer to advance the preformed margin into the final former and toward the operating zone of said meachine.
 18. A machine as set forth in claim 15 wherein the machine has a work feeding mechanism, and the inner end gage portion of the preformer is aligned with the path of feed effected by the work feeding mechanism, and the end gage is perforated to dump air delivered from said air stream groove.
 19. Mechanism for forming the margin of flexible sheet material to be hemmed, which material may range in different work pieces, respectively, in weight and/or stiffness, the mechanism comprising a hem securing tool, a work support movable toward and from the tool, at least a pair of margin formers mounted on the work support and having roll surfaces terminating in aligned end gages, an air stream groove extending in the respective roll surfaces substantially normal to the end gages, and control means including a nozzle for directing air flow with different velocities in the air stream grooves toward the end gages, said control means including a regulator means responsive to the degree of weight and/or stiffness of the sheet material for providing adequate air flow to effect engagement of the sheet material edgewise with the gages without incurring buckling of the material along the roll surfaces.
 20. A hemming machine comprising stitch forming instrumentalities, a work supporting means adjacent thereto, at least one margin preformer disposed for receiving work on said means and spaced from the instrumentalities and having a roll portion terminating in an inner edge gage, a final margin former intermediate the preformer and said instrumentalities, the final former having an edge gage aligned with that of the preformer and a portion shaped with a cross section tapering to a flattened exit end, the work engaging surface of the preformer being formed with an air stream groove extending toward the roll portion to extend the Bernouilli effect when air flow is directed between said surface and the work and toward the inner edge gage, the margin forming peripheries of the cross sections of the preformer and final former being substantially equal in length, and mechanism for advancing the work over the work supporting means and towards the instrumentalities to be progressively formed and hemmed when its margin is in contact with the aligned edge gages. 